CBSE Class 9 Science Why do we fall ill Sure Shot Questions Set 02

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ASSIGNMENT QUESTIONS SET - 2

CHAPTER - 13

WHY DO WE FALL ILL

1. What does the word health mean? [1 Mark]

Answer:
1. Health is a state of complete physical, mental and social well-being.
2. It does not simply mean absence of disease or physical fitness.

Teacher's Note:
a) Health is defined by the WHO as physical, mental and social well-being.
b) Emphasize that social and mental dimensions are just as important as physical well-being.

2. Name any two Symptoms of diseases. [1 Mark]

Answer:
1. Cough.
2. Loose motions.

Teacher's Note:
a) Symptoms are indicators that show the presence of a disease in the body.
b) Mention that symptoms are felt by the patient, such as headache or cough.

3. The disease which last for only a short period of time is called...................... [1 Mark]

Answer:
1. Acute Disease.

Teacher's Note:
a) Acute diseases appear suddenly and last for a very short duration.
b) Common cold is a classic example of an acute disease.

4. State whether Tuberculosis is a Chronic Disease or Acute Disease. [1 Mark]

Answer:
1. Chronic Disease.

Teacher's Note:
a) Tuberculosis lasts for a long time, often years, making it a chronic disease.
b) Chronic diseases have long-term drastic effects on human health.

5. Mention the causal organism for Sleeping sickness. [1 Mark]

Answer:
1. Trypanosoma.

Teacher's Note:
a) Trypanosoma is a protozoan parasite that causes sleeping sickness.
b) It is transmitted by the tsetse fly vector.

6. Sleeping sickness is caused by................................................... [1 Mark]

Answer:
1. Protozoa (Trypanosoma).

Teacher's Note:
a) Sleeping sickness is a vector-borne parasitic disease.
b) The causative agent belongs to the kingdom Protista.

7. Elephantiasis is caused by.................................................... [1 Mark]

Answer:
1. Filarial worm (Wuchereria bancrofti).

Teacher's Note:
a) Elephantiasis is also known as filariasis.
b) It leads to chronic swelling in the lower limbs.

8. Mention two Air born diseases. [1 Mark]

Answer:
1. Common cold.
2. Tuberculosis.

Teacher's Note:
a) Air-borne diseases spread through droplets released by coughing or sneezing.
b) Pneumonia and influenza are other common examples.

9. Mention two Sexually Transmitted Diseases. [1 Mark]

Answer:
1. AIDS.
2. Syphilis (or Gonorrhoea).

Teacher's Note:
a) These infections spread primarily through sexual contact.
b) Hepatitis B can also be sexually transmitted.

10. Mention two Viral Diseases. [1 Mark]

Answer:
1. Common cold.
2. Influenza (or Dengue / AIDS).

Teacher's Note:
a) Viral diseases are caused by pathogenic viruses.
b) They generally cannot be cured using common antibiotics.

11. What is called vector. Give one example. [2 Marks]

Answer:
1. Vectors are organisms that transmit infectious pathogens from an infected animal or human to another.
2. Example: Female Anopheles mosquito transmits malaria.

Teacher's Note:
a) Define vectors clearly as intermediate carriers.
b) Distinguish between vector and pathogen.

12. Give two examples of Chronic diseases. [1 Mark]

Answer:
1. Diabetes.
2. Elephantiasis (or Tuberculosis / Cancer).

Teacher's Note:
a) Chronic diseases persist for a long duration, often a lifetime.
b) They cause prolonged damage to health.

13. Distinguish between Infectious and Non-infectious diseases. [3 Marks]

Answer:
1. Infectious diseases are caused by micro-organisms and can spread from an infected person to a healthy person.
2. Non-infectious diseases are not caused by infectious agents and do not spread from person to person.
3. Examples of infectious diseases include malaria and tuberculosis, while non-infectious diseases include cancer and diabetes.

Teacher's Note:
a) Focus on the causative agents and transmissibility.
b) Use a clear comparative approach in points.
c) Give relevant examples for both categories.

14. Write a short notes on Small Pox. [3 Marks]

Answer:
1. Smallpox was a highly contagious and disfiguring viral disease caused by the variola virus.
2. It caused high fever and characteristic fluid-filled blisters all over the body.
3. Through extensive vaccination programs led by the WHO, smallpox has been completely eradicated globally.

Teacher's Note:
a) Highlight that smallpox is now a historically eradicated disease.
b) Mention the causal virus and major symptoms.
c) Emphasize the success of vaccination in disease eradication.

15. What is immunity? Write short notes on it. [3 Marks]

Answer:
1. Immunity is the balanced state of multicellular organisms having adequate biological defenses to fight infection, disease, or other unwanted biological invasion.
2. It involves the immune system recognizing foreign antigens and producing specific antibodies or lymphocytes to neutralize them.
3. Immunity can be innate (present from birth) or acquired (developed after exposure to pathogens or vaccination).

Teacher's Note:
a) Define immunity as the body's defense mechanism.
b) Distinguish briefly between innate and adaptive immunity.
c) Mention the role of white blood cells and antibodies.

16. What is Vaccination? Give the details, how it works in human body. [4 Marks]

Answer:
1. Vaccination is the administration of antigenic material to stimulate an individual's immune system to develop adaptive immunity to a pathogen.
2. When a vaccine is introduced, the body's immune system recognizes the weakened or dead microbe as a foreign threat.
3. The immune system produces specific antibodies against it and retains memory cells of the pathogen.
4. If the body is exposed to the actual infectious disease later, the memory cells recognize it rapidly and eliminate the infection before the disease can manifest.

Teacher's Note:
a) Explain the principle of immunological memory.
b) Describe how weakened or dead microbes are used safely.
c) Mention antibody production and rapid secondary response.
d) Relate vaccination to disease prevention on a community scale.

17. Write three reasons for Cancers. [3 Marks]

Answer:
1. Exposure to carcinogens such as tobacco smoke, chemicals, and radiation.
2. Genetic predispositions and inherited mutations in DNA.
3. Infection by certain oncogenic viruses or chronic inflammation.

Teacher's Note:
a) Focus on factors leading to uncontrolled cell division.
b) Mention environmental and genetic factors.
c) Highlight lifestyle habits like smoking.

18. What are the basic five principles of treatment for diseases. [5 Marks]

Answer:
1. Reduce the effects of the disease by taking medicines to bring down symptoms like fever, pain, or loose motions.
2. Kill the causative microorganism using appropriate drugs like antibiotics or anti-viral medications.
3. Bed rest to conserve energy so that the body can channel resources toward healing.
4. Supportive therapy such as proper nutrition and hydration to strengthen the immune system.
5. Prevent the spread of infection through isolation and hygienic practices.

Teacher's Note:
a) Divide treatment principles into symptom management and pathogen eradication.
b) Emphasize the importance of resting and energy conservation.
c) Mention nutritional support for recovery.
d) Include preventive measures against spreading disease.

19. How Hygiene could help you to maintain good health and mention five situations to take care about health. [4 Marks]

Answer:
1. Hygiene prevents the entry and multiplication of pathogenic microorganisms, thereby keeping infectious diseases at bay.
2. Situation 1: Washing hands thoroughly before eating food.
3. Situation 2: Maintaining cleanliness after using the toilet.
4. Situation 3: Ensuring safe drinking water and clean food storage.
5. Situation 4: Keeping living surroundings clean and preventing stagnant water accumulation to avoid mosquito breeding.
6. Situation 5: Maintaining personal cleanliness like bathing regularly and trimming nails.

Teacher's Note:
a) Define personal and public hygiene.
b) List practical day-to-day situations clearly.
c) Connect cleanliness directly to vector and pathogen control.
d) Emphasize food and water safety.

20. How does the health of an organism depend upon the surroundings? [3 Marks]

Answer:
1. Physical surroundings like clean air, pure water, and a pollution-free environment are vital for proper body functioning.
2. Social environment, including living conditions and economic status, determines access to proper nutrition and healthcare.
3. Poor surroundings with garbage accumulation and stagnant water promote vector breeding, leading to frequent illnesses.

Teacher's Note:
a) Differentiate between physical and social environment.
b) Link surroundings directly to community health.
c) Explain how pollution and poor sanitation cause disease.

21. What do we mean by “disease”? [2 Marks]

Answer:
1. A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism.
2. It is characterized by specific signs and symptoms, indicating that the body is not functioning properly.

Teacher's Note:
a) Define disease as discomfort or disordered body functioning.
b) Distinguish between being healthy and being free of disease.

22. What are symptoms? [2 Marks]

Answer:
1. Symptoms are physical or mental features that indicate a condition of disease, such as headache, cough, or fever.
2. They are felt and reported by the patient.

Teacher's Note:
a) Emphasize that symptoms are subjective indicators experienced by the patient.
b) Contrast symptoms with objective clinical signs.

23. How do you distinguish between acute and chronic diseases? [3 Marks]

Answer:
1. Acute diseases last for a very short duration, whereas chronic diseases last for a long time, even a lifetime.
2. Acute diseases do not cause major long-term body damage, whereas chronic diseases have drastic long-term effects on health.
3. Examples of acute diseases include the common cold, while chronic diseases include diabetes and tuberculosis.

Teacher's Note:
a) Base the distinction on duration and severity.
b) Mention recovery rates for both types.
c) Provide standard examples.

24. What are the various causes of diseases? [3 Marks]

Answer:
1. Immediate causes include infectious agents like bacteria, viruses, fungi, and parasites.
2. Contributing causes include lack of nourishing food, poor economic status, and lack of clean drinking water.
3. Genetic differences and internal organ malfunctions also act as root causes for certain diseases.

Teacher's Note:
a) Differentiate between immediate and contributing causes.
b) Mention biological pathogens as well as environmental factors.
c) Highlight nutritional deficiencies.

25. Name some common infectious diseases [2 Marks]

Answer:
1. Common cold, influenza, and tuberculosis.
2. Malaria, cholera, and typhoid.

Teacher's Note:
a) List common bacterial and viral infections. b) Mention water-borne and air-borne examples.

26. Explain the effect of antibiotic penicillin on bacterial cells. [3 Marks]

Answer:
1. Penicillin blocks the bacterial processes that build cell walls.
2. Without a functional cell wall, bacteria cannot withstand the osmotic pressure from their surroundings.
3. Consequently, the bacterial cells burst and die.

Teacher's Note:
a) Explain the specific biochemical target of penicillin (cell wall synthesis).
b) Describe osmotic bursting in bacteria.
c) Mention that this mechanism is specific to bacterial cells.

27. Why are human cells not affected by penicillin? [2 Marks]

Answer:
1. Human cells do not possess cell walls; they only have a cell membrane.
2. Since penicillin targets the synthesis of the bacterial cell wall, it has no biochemical pathway to attack in human cells.

Teacher's Note:
a) Contrast animal cell structure with bacterial cell structure.
b) Explain selective toxicity of antibiotics.

28. Why are antibiotics ineffective against viruses? [2 Marks]

Answer:
1. Viruses do not have their own cellular machinery or cell walls for antibiotics to target.
2. Instead, viruses live and reproduce inside host cells, using the host's metabolic machinery.

Teacher's Note:
a) Highlight the acellular nature of viruses.
b) Explain that antibiotics work only against living bacterial processes.

29. How do communicable or infectious diseases spread? [3 Marks]

Answer:
1. Through air via droplets released by coughing and sneezing (e.g., tuberculosis).
2. Through contaminated food and water (e.g., cholera and typhoid).
3. Through vectors like mosquitoes and through sexual contact or direct physical touch.

Teacher's Note:
a) List various modes of transmission clearly.
b) Differentiate between direct and indirect contact.
c) Give relevant examples for each mode.

30. How does AIDS spread? [3 Marks]

Answer:
1. Through sexual contact with an infected person.
2. Through transfusion of blood contaminated with the HIV virus.
3. From an infected mother to her child through breastfeeding or during childbirth.

Teacher's Note:
a) Identify HIV as the causative agent for AIDS.
b) List bodily fluid transmission routes.
c) Clarify that casual contact does not spread HIV.

31. What are vectors? Name some vector transmitted diseases. [2 Marks]

Answer:
1. Vectors are organism intermediaries that transmit infectious pathogens from an infected individual to another.
2. Examples of vector transmitted diseases include malaria, dengue, and filariasis.

Teacher's Note:
a) Vectors are mostly blood-sucking insects like mosquitoes and flies.
b) Controlling vector populations is key to preventing these diseases.

32. The disease-causing microbes enter the body through different means. Where do they go then?. Do all microbes go to the same tissue or organ, or do they go to different ones? [3 Marks]

Answer:
1. After entering the body, microbes go to different organs and tissues based on how they enter.
2. Microbes entering through air generally go to the lungs, while water-borne microbes go to the gut lining.
3. Not all microbes go to the same tissue or organ; different pathogens target specific tissues.

Teacher's Note:
a) The point of entry dictates the initial target organ for many infections.
b) Some pathogens like HIV spread throughout the lymph nodes and immune cells.
c) Tissue specificity determines the specific symptoms produced.

33. The signs and symptoms of a disease depend upon the tissue or organ targeted. Explain. [3 Marks]

Answer:
1. The manifestations of a disease depend on the targeted tissue or organ.
2. If lungs are targeted, symptoms like breathlessness and cough occur, whereas liver targeting causes jaundice.
3. The body's immune response also creates localized inflammation at the target site.

Teacher's Note:
a) Different body parts have distinct functions, leading to different symptom profiles.
b) Pathogens disrupt the normal physiological activity of the specific organ.
c) Recognizing targeted organs helps in accurate clinical diagnosis.

34. How does HIV damage our body? [3 Marks]

Answer:
1. The Human Immunodeficiency Virus enters the immune system, specifically targeting white blood cells.
2. It progressively destroys the body's immune cells, reducing the body's ability to fight minor infections.
3. Ultimately, the immune system becomes so weak that the body cannot fight off everyday infections, leading to fatal complications.

Teacher's Note:
a) HIV attacks the immune system directly rather than causing a single localized disease.
b) The resulting condition is known as Acquired Immuno Deficiency Syndrome.
c) Patients succumb to secondary infections like tuberculosis.

35. How do we kill microbes? [2 Marks]

Answer:
1. We use specific medicines like antibiotics to kill bacteria and antimicrobial drugs for other pathogens.
2. These drugs block biochemical pathways crucial for the survival of the microbes.

Teacher's Note:
a) Antibiotics target bacterial cell wall synthesis or protein creation.
b) Viruses lack their own pathways, making them resistant to standard antibiotics.

36. What feature of our body protects us from catching infectious diseases? [2 Marks]

Answer:
1. The immune system is the primary defense mechanism of our body against infectious diseases.
2. Specialized cells actively seek out and destroy invading pathogens before they establish severe illness.

Teacher's Note:
a) White blood cells play a major role in recognizing foreign antigens.
b) Physical barriers like skin and mucous membranes also block entry.

37. Describe the principle behind vaccination. [3 Marks]

Answer:
1. Vaccination introduces weakened or dead microbes into the body to stimulate the immune system.
2. The immune system recognizes these harmless antigens and produces specific memory cells.
3. When the actual infectious microbe enters later, the body remembers it and destroys it rapidly.

Teacher's Note:
a) Vaccines mimic natural infections without causing the actual disease.
b) Memory cells ensure long-lasting protection against specific pathogens.
c) Mass vaccination helps achieve herd immunity in populations.

38. Name some diseases for which vaccines are available. [2 Marks]

Answer:
1. Vaccines are available for polio, tetanus, diphtheria, and measles.
2. Other notable examples include tuberculosis, hepatitis B, and pertussis.

Teacher's Note:
a) Childhood immunization schedules include many of these vaccines.
b) Universal immunization programs help eradicate severe global diseases.

39. Who were awarded nobel prize for discovery of treatment of peptic ulcer? [1 Mark]

Answer:
Robin Warren and Barry Marshall were awarded the Nobel Prize for discovering the bacterium Helicobacter pylori as the cause of peptic ulcers.

Teacher's Note:
a) Their discovery revolutionized the medical treatment of ulcers using antibiotics.

40. List some general principles of prevention. [3 Marks]

Answer:
1. Prevent exposure to infectious microbes by providing safe drinking water and clean environments.
2. Prevent airborne infections through proper ventilation and overcrowding control.
3. Boost the immune system by consuming adequate, nourishing food and maintaining general health.

Teacher's Note:
a) Public hygiene plays a major role in general disease prevention.
b) Strong immunity reduces vulnerability even if exposure occurs.
c) Vector control prevents vector-borne infections.

41. State any two conditions essential for good health. [2 Marks]

Answer:
1. Maintaining proper physical and social well-being.
2. Access to clean drinking water and balanced nutritional food.

Teacher's Note:
a) Good health encompasses physical, mental, and social dimensions.
b) Environmental hygiene directly impacts personal health status.

42. State any two conditions essential for being free of disease. [2 Marks]

Answer:
1. Maintaining a clean personal and domestic environment.
2. Consuming a balanced diet that provides adequate nutrition.

Teacher's Note:
a) Absence of disease is not identical to complete physical health.
b) Personal hygiene keeps harmful pathogens away from the body.

43. Are the answers to the above questions necessarily the same or different? Why? [3 Marks]

Answer:
1. The answers are different because being free of disease is not the same as being in good health.
2. A person can be free of disease and still experience poor mental or social well-being.
3. Good health reflects overall physical, mental, and social harmony, whereas disease-free status means no specific physical ailment.

Teacher's Note:
a) Health is a state of complete well-being, while disease freedom is narrower.
b) Economic and social conditions influence overall health.
c) A diseased person cannot experience true good health.

44. List any three reasons why you would think that you are sick and ought to see a doctor. If only one of these symptoms were present, would you still go to the doctor? Why or why not? [4 Marks]

Answer:
1. Three reasons to suspect sickness include persistent headache, continuous fever, and chronic loose motions.
2. Yes, even if only one symptom is present, a doctor should be consulted.
3. A single symptom can be an early warning sign of a serious underlying disease.
4. Early diagnosis and treatment prevent minor illnesses from becoming severe health complications.

Teacher's Note:
a) Symptoms indicate that something is functioning improperly in the body.
b) Ignoring a single symptom may lead to chronic conditions.
c) Professional diagnosis ensures appropriate medication use.
d) Preventive healthcare reduces overall medical burden.

45. In which of the following case do you think the long-term effects on your health are likely to be most unpleasant? a) if you get jaundice, b) if you get lice, c) if you get acne. Why? [3 Marks]

Answer:
1. The long-term effects on health are likely to be most unpleasant if you get jaundice.
2. Jaundice is a systemic disease that severely affects liver function and causes prolonged weakness.
3. Acne and lice are localized external conditions that generally do not cause long-term internal organ damage.

Teacher's Note:
a) Systemic infections impact overall body functioning.
b) Liver impairment disrupts digestion and metabolism significantly.
c) External parasites and skin issues clear up faster with proper hygiene.

46. Why we are normally advised to take bland and nourishing food when we are sick? [2 Marks]

Answer:
1. Bland food is easy to digest, reducing the workload on a weakened digestive system.
2. Nourishing food provides essential nutrients required for tissue repair and recovery.

Teacher's Note:
a) Illness temporarily impairs digestive capacity.
b) Proper nutrition accelerates the healing process.

47. How are acute diseases different from chronic diseases? [3 Marks]

Answer:
1. Acute diseases last for a very short period of time and do not cause long-term health effects.
2. Chronic diseases last for a long time, often a lifetime, and cause severe long-term damage.
3. Examples of acute diseases include the common cold, while chronic diseases include tuberculosis and diabetes.

Teacher's Note:
a) Duration is the primary distinguishing factor between these two categories.
b) Chronic conditions require prolonged medical management.
c) Acute conditions typically heal completely without lasting damage.

48. What is the full form of AIDS? Name the causal organism. [2 Marks]

Answer:
1. AIDS stands for Acquired Immuno Deficiency Syndrome.
2. The causal organism is the Human Immunodeficiency Virus (HIV).

Teacher's Note:
a) AIDS represents the late stage of HIV infection.
b) It impairs the body's natural defense mechanism against pathogens.

49. State two conditions essential for keeping good health. [2 Marks]

Answer:
1. Maintaining personal and social hygiene.
2. Consuming a balanced diet with proper nutritional value.

Teacher's Note:
a) Good health requires both physical and environmental cleanliness.
b) Mental peace and social harmony are equally vital components.

50. Define (a) health (b) disease. [2 Marks]

Answer:
1. Health is a state of complete physical, mental, and social well-being, and not merely the absence of disease.
2. Disease is a condition of malfunctioning of the body or mind that causes discomfort and disrupts normal activities.

Teacher's Note:
a) Health is multidimensional and depends on lifestyle and environment.
b) Diseases can be infectious or non-infectious in origin.

51. Why are antibiotics not effective for viral disease? [2 Marks]

Answer:
1. Viruses do not possess their own metabolic machinery or cell walls like bacteria.
2. Antibiotics work by blocking bacterial biochemical pathways, which viruses do not use.

Teacher's Note:
a) Viral replication occurs inside host cells using host machinery.
b) Antiviral drugs are required specifically to target viral infections.

52. Explain giving reasons -(a) Balanced diet is necessary for maintaining health body. (b) Health of an organism depends upon the surrounding environmental conditions. [4 Marks]

Answer:
1. A balanced diet provides all essential nutrients, vitamins, and minerals required for proper bodily functions.
2. It supplies energy and materials necessary for growth, immunity, and tissue repair.
3. The surrounding environment dictates exposure to disease-causing vectors and pathogens.
4. Clean surroundings, proper sanitation, and safe drinking water prevent infections and preserve health.

Teacher's Note:
a) Nutrition fuels every physiological process in the human body.
b) Unhygienic surroundings increase microbial proliferation.
c) Community hygiene supports individual well-being.
d) Balanced intake prevents deficiency disorders.

53. Explain the Natural and acquired immunity? [3 Marks]

Answer:
1. Natural immunity is present from birth and provides innate, non-specific defense mechanisms against various pathogens.
2. Acquired immunity is developed during a person's lifetime through exposure to infections or via vaccination.
3. Acquired immunity is highly specific and retains a memory of past pathogens for faster defense.

Teacher's Note:
a) Innate immunity acts as the first line of defense.
b) Vaccination builds acquired immunity artificially.
c) Lymphocytes are key components of acquired immunity.

54. What are the two ways to treat an infectious disease? [2 Marks]

Answer:
1. One way is to reduce the effects of the disease by using symptomatic treatment and medicines.
2. The second way is to kill the causative microbes using appropriate drugs such as antibiotics.

Teacher's Note:
a) Symptomatic treatment relieves pain and fever while the body heals.
b) Antimicrobial drugs eliminate the underlying infectious agents.

55. What do the sign and symptoms indicate if person is suffering from any disease? Based on the duration of diseases what are the difference between categories of diseases? Diffrentiate between them giving one example of each. [4 Marks]

Answer:
1. Signs and symptoms indicate that a specific part or tissue of the body is malfunctioning due to an infection.
2. Diseases are categorized based on duration into acute diseases and chronic diseases.
3. Acute diseases last for a short duration and heal completely, such as the common cold.
4. Chronic diseases last for a long time, often a lifetime, and cause long-lasting damage, such as tuberculosis.

Teacher's Note:
a) Symptoms provide clues for medical diagnosis.
b) Duration defines the severity and recovery timeline.
c) Chronic conditions require prolonged care.
d) Acute conditions resolve rapidly with proper treatment.